An Efficient Modern Strategy to Screen Drug Candidates Targeting RdRp of SARS-CoV-2 With Potentially High Selectivity and Specificity

Desired drug candidates should have both a high potential binding chance and high specificity. Recently, many drug screening strategies have been developed to screen compounds with high possible binding chances or high binding affinity. However, there is still no good solution to detect whether those selected compounds possess high specificity. Here, we developed a reverse DFCNN (Dense Fully Connected Neural Network) and a reverse docking protocol to check a given compound’s ability to bind diversified targets and estimate its specificity with homemade formulas. We used the RNA-dependent RNA polymerase (RdRp) target as a proof-of-concept example to identify drug candidates with high selectivity and high specificity. We first used a previously developed hybrid screening method to find drug candidates from an 8888-size compound database. The hybrid screening method takes advantage of the deep learning-based method, traditional molecular docking, molecular dynamics simulation, and binding free energy calculated by metadynamics, which should be powerful in selecting high binding affinity candidates. Also, we integrated the reverse DFCNN and reversed docking against a diversified 102 proteins to the pipeline for assessing the specificity of those selected candidates, and finally got compounds that have both predicted selectivity and specificity. Among the eight selected candidates, Platycodin D and Tubeimoside III were confirmed to effectively inhibit SARS-CoV-2 replication in vitro with EC50 values of 619.5 and 265.5 nM, respectively. Our study discovered that Tubeimoside III could inhibit SARS-CoV-2 replication potently for the first time. Furthermore, the underlying mechanisms of Platycodin D and Tubeimoside III inhibiting SARS-CoV-2 are highly possible by blocking the RdRp cavity according to our screening procedure. In addition, the careful analysis predicted common critical residues involved in the binding with active inhibitors Platycodin D and Tubeimoside III, Azithromycin, and Pralatrexate, which hopefully promote the development of non-covalent binding inhibitors against RdRp.

Identifying Age-Related Risk Factors in COVID-19 Independent of Disease Severity (preprint)

COVID-19 emerged as the most lethal pandemic in the last century. Although it can affect persons with any age, patients with advanced age represent a significantly higher fraction of severe disease. The molecular and cellular mechanisms that render patients with advanced age susceptible to severe disease remains unknown. Here we revealed that older subjects (>=30 years) had significantly elevated levels of anti-inflammatory cytokine IL-10, but no change in any of the pro-inflammatory cytokines. While an expansion of NKT cell fraction was observed in older patients, a decrease in CD8+ T cell fraction was observed in these patients. In addition, older subjects had a delayed humoral response measured as IgM and IgG levels. Overall, these patients had significantly elevated viral load compared to young subjects. These data demonstrate altered early inflammatory and antiviral responses contributing to the age-related susceptibility to COVID-19.Funding Statement: This study was supported by funding from Beijing Nova Program Interdisciplinary Cooperation Project (DC; No. Z191100001119021), Chinese PLA General Hospital Youth Project (DC; No.QNF19074) and China 13th Five-year National Key Grant (LXX; No.2018ZX09201013). Declaration of Interests: The authors declare that there are no competing interests.Ethics Approval Statement: This study was approved by the ethics committee of Guangzhou Eighth People’s Hospital, with a waiver of informed consent.

Type I Interferon Limits Viral Dissemination-Driven Clinical Heterogeneity in a Native Murine Betacoronavirus Model of COVID-19 (preprint)

Emerging clinical data demonstrates that COVID-19, the disease caused by SARS-CoV2, is a syndrome that variably affects nearly every organ system. Indeed, the clinical heterogeneity of COVID-19 ranges from relatively asymptomatic to severe disease with death resultant from multiple constellations of organ failures. In addition to genetics and host characteristics, it is likely that viral dissemination is a key determinant of disease manifestation. Given the complexity of disease expression, one major limitation in current animal models is the ability to capture this clinical heterogeneity due to technical limitations related to murinizing SARS-CoV2 or humanizing mice to render susceptible to infection. Here we describe a murine model of COVID-19 using respiratory infection with the native mouse betacoronavirus MHV-A59. We find that whereas high viral inoculums uniformly led to hypoxemic respiratory failure and death, lethal dose 50% (LD50) inoculums led to a recapitulation of most hallmark clinical features of COVID-19, including lymphocytopenias, heart and liver damage, and autonomic dysfunction. We find that extrapulmonary manifestations are due to viral metastasis and identify a critical role for type-I but not type-III interferons in preventing systemic viral dissemination. Early, but not late treatment with intrapulmonary type-I interferon, as well as convalescent serum, provided significant protection from lethality by limiting viral dissemination. We thus establish a Biosafety Level II model that may be a useful addition to the current pre-clinical animal models of COVID-19 for understanding disease pathogenesis and facilitating therapeutic development for human translation.

Severe SARS-CoV-2 infection is defined by a shift in the serum lipidome resulting in dysregulation of eicosanoid lipid immune mediators (preprint)

The COVID-19 pandemic has affected more than 10 million people worldwide with mortality exceeding3 half a million patients. Risk factors associated with severe disease and mortality include advanced age,4 hypertension, diabetes, and obesity.1 Clear mechanistic understanding of how these comorbidities5 converge to enable severe infection is lacking. Notably each of these risk factors pathologically disrupts6 the lipidome and this disruption may be a unifying feature of severe COVID-19.1-7 Here we provide the first in depth interrogation of lipidomic changes, including structural-lipids as well as the eicosanoids and docosanoids lipid mediators (LMs), that mark COVID-19 disease severity. Our data reveal that progression from moderate to severe disease is marked by a loss of specific immune regulatory LMs and increased pro-inflammatory species. Given the important immune regulatory role of LMs, these data provide mechanistic insight into the immune balance in COVID-19 and potential targets for therapy with currently approved pharmaceuticals.8

Severe SAR-CoV-2 infection in humans is defined by a shift in the serum lipidome resulting indysregulation of eicosanoid immune mediators (preprint)

The COVID-19 pandemic has affected more than 10 million people worldwide with mortality exceeding half a million patients. Risk factors associated with severe disease and mortality include advanced age,hypertension, diabetes, and obesity. Clear mechanistic understanding of how these comorbidities converge to enable severe infection is lacking. Notably each of these risk factors pathologically disrupts the lipidome and this disruption may be a unifying feature of severe COVID-19. Here we provide the first in depth interrogation of lipidomic changes, including structural-lipids as well as the eicosanoids and docosanoids lipid mediators (LMs), that mark COVID-19 disease severity. Our data reveal that progression from moderate to severe disease is marked by a loss of specific immune regulatory LMs and increased pro-inflammatory species. Given the important immune regulatory role of LMs, these data provide mechanistic insight into the immune balance in COVID-19 and potential targets for therapy with currently approved pharmaceuticals.

Social Distancing and Personal Protective Measures Decrease Influenza Morbidity and Mortality (preprint)

Seasonal influenza (flu) is an underappreciated source of disease morbidity and mortality worldwide. While vaccination remains the cornerstone of influenza prevention, common measures practiced during the COVID-19 pandemic such as social distancing, the use of protective face masks, and frequent hand washing are rarely utilized during flu season. In this investigation, we examined the effect of these preventative measures in decreasing influenza burden this year. We examined three countries with major COVID-19 outbreaks i.e. China, Italy and the United States, and compared the flu activity this year to the average of the last 4 years (2015-2019). We found that this year in China and Italy, there was a significantly steeper decline of flu cases than average, which correlated with an increase in positive COVID-19 case reports in those countries. These "averted" cases can be translated into a substantial decrease in morbidity and mortality. As such, we conclude that the current COVID-19 pandemic is a reminder that behavioral measures can decrease the burden of communicable respiratory infections, and these measures should be adopted to an extent during normal influenza season.